Antenna tuner



Jan. 14, 1958 w. E. PATTERSN 2,820,222

ANTENNA TUNER 2 Shee'ts-Sheet l Filed May 4, 1954.

. Jan- 14 1958 'v w. E. PATTERSON 2,820,222

ANTENNA TUNER IN VEN TOR. WILLIAM E. PATTERSON United States Pateti C F Fla., a corporation of Florida Application May 4, 1954, Serial No. 427,472 30 Claims. (Cl. 343-861) This invention relates to impedance matching circuits and has particular reference to methods and apparatus for automatically tuning an antenna to a radio transmitter.

In the coupling of energy from a first impedance toa second impedance, it is well known that such impedances. must be matched for ei'lcient operation. A typical eX- ample in which such matching is important occurs in the transmission of electro-magnetic signals. Thus, an antenna must be properly tuned to a transmitter if maximum electrical efliciency is to be realized. Various arrangements for performing this function have been employed including manually tuned circuits between the transmitter and the anntenna and various automatic circuits relying, in some instances, the R.F. signals from the transmitter. The problem becomes particularly acute where the transmitter operates on a great number of dilerent frequencies which necessitates the retuning of the antenna whenever the transmitter is rechanneled. Further, various weather conditions' canA change the antenna characteristics to detune the antenna while the transmitter is operating on a single channel.

An example wherein the above-outlined problems have been particularly diflicult to overcome occurs in aircraft radio transmitters wherein a large number of channels are utilized. In switching between channels, it is greatly de' sirable that the antenna be matched to the transmitter within as short a time as possible after such rechanneling. Further, it is necessary that the antenna be con-- tinuously tuned to the transmitter during operation there-' of to accommodate changes in the antenna characteristics due to the change from ground to airborne operation or to climatic conditions such as rain, ice, heat and cold.

The present invention provides an antenna tuner that satisles the above-outlined conditions in radio transmission. Sensing circuitry is provided between the transmitter output and the antenna to generate signals indicative of the impedance mismatch therebetween. Such signals are supplied to circuits which adjust tuning elements in attempting to tune the antenna to the transmitter. Further circuitry responsive to the adjustment ot the tuning elements selectively arranges the tuning elements in the proper relation by the actuation of switching means to permit their adjustment to tune the antenna to the transmitter.

' These and further advantages of the invention will be more readily understood when the following description is read in connection with the accompanying'drawings in which: v

Figure 1 is a schematic circuit diagram partially in block form of an antenna tuner constructed in accordance with the present invention;

Figure 2 is a schematic circuit diagram of one form ot a sequence circuit that may be employed in the tuner illustrated in Figure l; and

Figures 3A, 3B, 3C and 3D are schematic circuit diagrains illustrating the various relationships between the on information other than.,

through an armature ice tuning elements and the antenna that may be necessary to match an antenna to a transmitter. Referring to an illustrative embodiment of the invention in greater detail with particular reference to Figure A1, an antenna 10 must be matched to the output impedance of a transmitter power amplifier 11 in order to provide for efficient operation of a multi-channel radio transmitter (not shown). For clarity, the signal path from the transmitter power amplifier 11 to the antenna 10 is designated by heavy connecting lines to distinguish it from the control circuits.

Inserted in the output of the amplifier 11 are a magnitude sensitive bridge 12 and a phase sensitive bridge 13, both bridges being of conventional design. The magnitude sensitive bridge 12 is constructed so that it responds with zero signal when it looks into a predetermined magnitude of impedance while the phase sensitive bridge 13 sends out zero signal when it looks into a resonant condition which is, of course, zero phase angle.

Fromthephase sensitive bridge 13, the R.F. signals are coupled through a variable condenser 14 joined by conduits 15l and 16 to the front and back contacts of a relay 17 actuating an armature 18. The condenser 14 may comprise any conventional variable condenser and is shown herein as having high and low sections connected to the conduits 15 and 16, respectively. The particular condenser illustrated is an air condenser constructed so that the rotor thereof martes one revolution while the capacity is varied from the minimum value to the maximum value. After passing through its maximum value, the capacity of the condenser 14 will abruptly switch to 4its minimum value. An example of such a cori-v denser niay be found in the Patent No. 1,631,360 to Clark. It will be understoodthat other variable condensers may be substituted in the circuit.

The R.F. signals are next coupled by a conduit 19 to the upper end of a variable inductance 20. As shown in Figure l, the lower end of the inductance 20 is joined by a conduit 34 to a bach and a front contact of a relay 21 actuating armatures 22 and 23. When deenergized, the armature 22. joins the back contact of the relay 21 through a conduit 33 to the upper end of a second variable inductance 24, the lower end of the inductance 24 being tied to ground through aconduit 25 and an armature26 actuated by a relay 21.

The upper end of the inductance 2i) is also connected 26 of the relay 2'7 and an armature 2.9 of a relay 30 to a conduit 31 leading to the antenna 10. Thus, it will be apparent from inspection that Figure 1 shows the variable condenser 14 and the variable inductances 20 and 24 connected in circuit with the antenna 10 as illustrated in Figure 3A.

in certain instances, as expiained in detail hereinafter, it is desirable to connect the variable inductances 20 and 24 in parallel relation. rlhis may be accomplished by the energization of the relay 21 which joins the upper ends ot' me inductances 20 and and the conduit 36 and the armature 22. Similarly, the lower ends of the inductances 20 and 24 are joined by the conduit 34, the armature 23 and a conduit 35 so that the resultant circuit is as shown in Figure 3B.

In other circumstances, it is desirable to insert the inductances 20 and 24 in series between the source of Of course, while the variable inductances 20 and 24 are in series relation with the antenna 1 0 and source of 24 through a conduit 32r R. F. signals, the relay inductances 20 and 24 Figure 3D.

It is necessary to render the antenna more capacitive under certain conditions. Therefore, a condenser 36 may be selectively inserted between the inductances 20 and 24 and the antenna 10 by the energization of the relay 30.

At this time, it may be well to pointout 'that the variable inductances 20 and 24 are preferablyof the variometer type, a variable inductance that is well known and comprises a pair of concentrically mounted coils rotatable with respect to each other. In this instance, the rotating coils of a pair of variometers are vmechanically joined together so that the in'dnctancesv 20 andl 24 are effectively ganged and adjusted as a unit. Since, it is,de. sirable to provide a large range of inductan'ce in order to tune a wide variety of antennas to a radio'tr'ans'mitter, two variometers are preferably employed in thev antenna tuner. Thus, while in parallel the variable inductances 20v and 24 may be adjusted from a low minimum value through a certain range and while in series, they may be adjusted through another range to a high maximum value. Of course, if such an extended range i's `not. necessary, a single variometer could' be employed. Further, other"` variable inductances maybe substituted' for'the variom'e, ters within the scope of the present invention.

In matching the antenna 10 to the amplifier '11, it is preferable to commence the automatic tuning operation with. theV tuning elements connected in a predetermined manner and adjusted to a predetermined'valiie rangeV o'rf point. Thus, it hasy been found preferable to initially employ the circuit arrangement illustrated in Figure' 3A. However, it may be that the tuning elementsV areV in any of the other arrangements illustrated' in Figures 3B, 3C

in parallel relation as shown'in and l3D or that the condenser 14 andthe nductancesfz" and 24 are not within the predeterminedrange whi ch in this instance, is any point near the maximum capaci; tance and inductance of the tuningelements, respectively. Therefore, provision must be made for setting up 'the circuit as illustrated in Figure 3A before the 'automatic tuning is initiated;

Circuit means for connecting the tuning 'elements as illustrated in Figure 3A includea plurality of relay actuated switches controlled by a switch 37 which'connects a D. C. source 38 to a terminal'X. The switch 37 may be closedk automatically in response to rechanneling of the associated radio transmitter (not shown) in which event it will be opened upon completion of such rechanneling.Vv

Alternatively, the switch 37 may be manually actuated. Terminal X, in turn, is joined to a plurality of relays for actuating the plurality of switches as will be indicated n detail below, the actual connections between only one terminal X and a relay being shown for si`m plicity. Of course, it will be understood thatasingle relay carrying a plurality of contacts may be employed to accomplish the same function performed by the plurality of relays disclosed.

Considering the setup or homing operation in detail, the closure ofthe switch 37 energizes a relay 39 which swings its armature 40 to a front contact thereof connected to the relay 17 through a conductor 41. This initiates the adjustment a point inits maximum capacity range.

A grounded reversible D. C. motor' 42 is tied' to the" armature 40 by a conductor 43 and drives a cam 44 through a conventional mechanical linkage' 45. The cam 44 is provided with a raised segment over 180' degrees and actuates-a following armature 46 between a pair of' contacts 47 and 48, the last-mentioned contact being connectedto the front contact of the relay 39. A D. C. j source 49 is joined to the armature 46 so that its engager` ment with the contact V48 results in the source`49 ener' gizing the relay 17 and the motor 42 during the interval Y,

the armature 40engages the front contact'of the relay 21 may be energized to place the ofthe variable condenser 14 to 39. The variable condenser 14 and the cam 44 are orientated on the mechanical linkage 45 so that the armature 46 will engage the contact 48 as long as the variable condenser 14 is in its minimum capacity range. Therefore, it will be apparent that the motor 42 will be energized by the source 49, assuming the relay 39 to be energized, while the condenser is being driven through its minimum capacity range.

However, the armature '46 is disengaged from the contact-4l8^when the condenser 14 reaches Vits maximum capacity range and this results in the deenergization of the motor 42 and the relay 17. Thus, the armature 13y will engagetheA conduit 15 leading to the maximum capacity section of the condenser 14 and the variable condenser 14 will stand in its maximum capacity range. In this manner, the condenser 14 is prepared for the automatic operation of the tuning circiuts.

ItV is also necessary to connect the variable inductances 20 and 24' in the relation shown in'Figure 3A with respect to the antenna 10 and to drive them to a point in their maximum range. The manner of obtaining the proper connections will be. explained in the description of the control circuits. In order to accomplish the latter function of adjustingl the' variable inductances 20 and 24 to a predetermined' maximum range, a relay 50 actuating: an armature 51 is energized'through the switch 3'] and the terminaly X. When thearmature 51 engages the front contact off the relay 5G', itconditions circuit means forv adjustingfthe inductances' 20 and 24 to their maximum range. These circuit means'include a cam 52 joined by afmechanical linkage 53 'to a'D.-C. motor S4, the cam 52 being provided with Van approximately 70 degree cut away portion, for example,y thisY angle not being critical. An armature 53' follows` the cam 52 and swings between contacts54'and 55, the latter contact being joined through a conductor 5.6 tov the frontfcontactof the relay Si). The mechanical linkage 53 also. drivesV the variable inductances l 20 "and'2'4,` the cani 52 and variable inductances 2li and 24 being, orientated thereon so that the armature 53 engages the contact 54 whenl these tuning elements are in the desired maximum range.

The armature 53 is energized by a source of D.C. potential 57a. It will be evident that when the cam S2 actuates the 'armature 53 into engagement with the contactf'55 and the relay 50`is energized, the motor 54 will be energized by the D.C. source 57a through the armature' 53, the conductor 56, the armature 51, conductorsl 57 andSStothebac'k. contact of a relay 59,' and a grounded armature 60 Yof the relay 591. The motor 54 will continue'to" rotate'until the armature 53 encounters thefcut away portion ofthe cam 52 which breaks the energizing'circuit. vAt. this point, the variable indnctances 20 and 24 willbe in the desired maximum range.

As mentioned above, variometers are preferably employed for the variable inductances 20 and 24 and due to their` nature, certain circuit arrangements must be employed therewith. Thus, it is well understood that the variometer inductance will vary from a maximum to a minimum to a maximum in 360 degrees relative rotation of the coils. However, for the purposes of the present invention, it is preferable to tune the antenna 10 while varying the inductance through a single cycle. In other words, only ydegrees rotation of the variometers is utilized. j

Toproyide, thismodefof operation, ya cam 61 with a following armature 62 swinging between contacts 63 and 64is.drivenvbythe mechanical linkage 53 from the motor 54. The contact 64 is joined through a conductor 65 to the relay 59, the other side of the relay 59 being connected to -a D.C. source 66 through a conductor 67 and anarmature 68 of av relay 69, this last-mentioned relay being joined to the terminal X andenergized when the switch 37 is closed. A cut away portion on the cam 61 is orientedY so .thatthe armature 62 swings to the contact 64 when the variometers are at minimum inductance. This .action energizes the relay 59 and disengages the armature 60 from the back contact thereof. Thus, a rectifier 70 normally in parallel with the armature 60 is inserted in series with the motor 54. The polarity of the rectifier 70 is chosen to preclude current ow in a direction through the motor 54 to cause further rotation of the variometers 20 and 24 in the same direction which would, of course, be utilizing the other 180 degrees rotation of the variometers. It will be evident that as soon as the motor 54 is rotated toward the maximum position on the desired side of the variometers 20 and 24, the relay 59 will be deenergized and the motor 54 will once again be grounded through the armature 60. Obviously, this arrangement could be eliminated if another type of variable inductance was employed. Further, the rectifier 70 and bypass 60 could be inserted in any rother suitable position in the motor circuit.

It willbe understood that the invention is not limited to the particular homing arrangement described above. Other similar homing means may be employed to adjust the tuning elements to a maximum range, to any other vdesired range or to any desired point. In addition, such homing means may be omitted from the tuner in certain instances.

To adjust the condenser 14 and the inductances 20 and 24 to attempt to tune the antenna 10 to the amplifier 11 while the circuit elements are connected as shown in Figure 3A, the output signals from both the magnitude sensitive bridge 12 and the phase sensitive bridge 13, which are conventionally D.-C. signals, are converted to A.C. signals in any convenient manner such as by chopv'ping in a vibrator (not shown) and passing through capacitors (not shown). The A.C. signals are then fed to 'ampliers 71 and 72 by conductors 73 and 74, respectively.

The output signals from the magnitude signal amplifier 71 are reoonverted in any conventional manner, such as by further contacts on the chopping vibrator, to corresponding D.C. potentials which are applied through a conductor 75 lto the D.C. drive motor 54, the other terminal of the drive motor normally being grounded through the conductor 58 and the armature 60. A relay 76 actuating an armature 77 is also connected across the krnotor 54.

The phase signal amplifier 72 applies error signals through a conductor 78 to the grounded D.-C. drive motor 42, a relay 79 having an armature 80 being connected across the motor 42. The armature 80 is joined to the armature 77 by a conductor 81 which is tied to a positive source of potential 82. The front contacts of the relays 76 and 79 are also joined by a conductor 83 which leads to a slow release relay 84 provided with an armature 85.

It should be noted that the signal from the magnitude sensitive bridge 12 may result in a positive or negative D.-C. voltage across the motor 54 according to whether the impedance the bridge 12 sees is too great or too small. Therefore, the motor 54 will respond in either direction to adjust the variable inductances 20 and 24 to attempt to remove the mismatch. The same is true for the phase sensitive bridge 13, the motor 42 adjusting the variable condenser 14 in a direction determined by the leading or lagging phase angle seen by the bridge 13.

Assuming that the switch 37 has been closed either manually or automatically in response to rechanneling of the radio transmitter, the tuning elements will preferably be arranged as illustrated in Figure 3A due to the deenergized condition of the relays 21 and 27 resulting from the operation of circuits to be described hereinafter. In addition, the condenser 14 and the variable inductances 20 and 24 will have been driven to their maximum ranges. Accordingly, opening vthe switch 37 results in an attempt to match ythe antenna to the output impedance of the transmitterl power amplifier 11. Thus, the magnitude 'sensitive bridge will respond with a D.C. error signal of .a positive or negative polarity if it looks into an impedance ymagnitude different than the output impedance of the 24 are'driven to their minimum value, the armature 62 following the cam 61 will enter thev cut away portion therein and engage the contact 64 to prevent further adjustment of the inductances 2u and 24 in the same physical direction.

Turning next to the phase sensitive bridge 13, it is set to generate error signals if it does not look into a resonant condition, i. e., zero phase angle. Thus, assuming a leading or laggingA phase angle condition, an error signal will be generated to cause the motor 42 to rotate in either direction to vary the capacity ot' the condenser 14. lt may `be that with the circuit arrangement shown in Figure 3A,

a resonant condition will be obtained and the motor 42 deeneigized due to a tacit of error signal. rlowever, it will be assumed tor the moment that during the tuning operation, the condenser i4 is driven through its maximum capacity atter the inductances 2o and 24 have been driven to their minimum vaine. At this point, provision has been made to switch the tuning elements. this runction is achieved by driving a cam oo oy the motor 4L, a tollowing armature b9 swinging between contacts 9U and 9L and being tied by a conductor 92 and the conductor ua to the reiay a9. in addition, the armature b9 is joined by the vconductor 92 and a conductor 93 to the armature o5 of the reiay 84. l

'l he cut away portion of the cam 88 is oriented thereon so that the armature 69 drops therein and engages the contact 9i when the condenser 14 has reached its maximum value. As assumed above, the inductances 20 and 24 have been driven to their minimum value causing the armature 62 to engage the contact 64. Accordingly, a Conductor 94 leading to a sequence circuit 95, which will be examined in detail hereinafter, is grounded through the series contacts 91 and 64. lt should be noted that the bach contact of the relay 84, connected to the contact 91 through a conductor 96, will not engage the armature S5 at this time. Thus, the slow release reiay S4 will be energized through the armature ttt) by the D.-C. source 82 since the motor 42 continues to drive the condenser 14 in response to error signals from the amplifier 72.

'the grounding puise furnished to the sequence circuit 95 on the conductor 94 will result in the energization of a conductor 9/ leading from the sequence circuit 95 to the relay 2i which, when energized, will connect the variable inductances 20 and 24 in parallel relation as shown in Figure 3B.

By placing the inductances 20 and 24 in parallel, a much lower value of inductance will be inserted between the antenna 10 and ground. In many instances, this arrangement will permit the impedance of the antenna 10 to be matched to the transmitter output. However, in the event that the antenna characteristics are such that the parallel combination of the variable inductances 20 and 24 remains at or is again driven to the minimum value thereof by the motor 54, provision is made to insert the condenser 36 in series therewith to render the antenna 10 capacitive. This operation will be explained in detail hereinafter.

Returning to the condition of the antenna tuner immediately after the interval in which the switch 37 was opened, it will be recalled that the tuning elements are arranged as shown in Figure 3A and have been driven to predetermined maximum value ranges. In the operation above, it was assumed that the inductances 20 and 24 were driven to their minimum value in attempting to tune the antenna 10 while the condenser 14 was driven through naam-22a "its maximum tvalue. It will next beassumed Athzttthe Aerror'si'gnal'fr'om themagriitude sensitive bridge I2 causes -the motor 541to 4vary thel inducta'nces 2`0fand '24 towards 'theirInaxim'unrvalue in attemptin'gto tune the antenna 10. This operation may result in the matching 'ofthe antenna1`0-tothe` amplier *1-1 or q'tlreyinduc'tan'ces 20 and 24 may-be driven vuntil they 'reach Jtheir*'maximum value. At *that point, i'provision' Ais made Lfor`:further-shiftingthe connectionsfof the Ituning elements, -such fu'nctiondrein'g 'performed -by'a cam 9;'8' cooperating with van -larmature follower99 swinging; between contacts i100"and 101.

'The armature v`99"is Igrounded"whilethe contact 101'is ytied to fa'relay 102 actuatin'gapair *of 'arm'atures"1'03 land 104 connected to the terminals thereof. The relay 102 risalso lcon'nectedo' the *back Contact 'of `a relay -1`0`5',ener gized by#the"switch"37 `and "actuatingan "armature "1'06 which is? joined to'aiDr-C. lsource 1107. The cam9'8'is provided '-witha "cut (away portion whi'chvis' Aorientated to cause the armature 99 to-Vengagetheconta'ct "101' when the inductances v20 a'r1`d"'24-taref'dr`iven "by" the' motor `54`tol their maximum value, 'thecam"`9`8 also beingdrive'n 'by the mechanicallinlcagelS. Thus, th'earmature`99 in'engaging the contact 101 Aprovides va ground `so'th'a'ttherelay 102 maybe en'ergiz'edibytthe DsCfsource v107 iflthe relay "10S-'is de'energized. vTh'is'results inthe' engagement of'the armature 103 lwitha :front corlta'ctvafhe relay 102 that is"joined by Va conductor 108 toth'e sequence circuit 95, the conductor 108b'e'ing' grounded through contacts in the 'sequence 'circuit y"95. lAccordingly,"the 'relay102' is eiectively-locked in position `irrespectivefofTurtherrotaton of the cam 98. Inaddition, ther armature '1'04f`engages 'another front contact of lthe relay 'T02 "torcomplete an energizing-circuit for the relay 27 "from thesource 107 through the armature 106, the armature 104 "andfconductor 109. "Thus, therelay "27 actuatesrthe larrriattlre 26 to placethe lvaiableinducta'nces 2G anfd 24'in"seri'es^with the antenna 10aa-shown in Figure -3 C.

vWith Vthe -'series arrangement illustrated in "Figure 3C, it`willusually -be necessary to reduce'the inductance of the-tuning elements 20-andf`24 to tune the antenna "10' to the amplifier 1-1. This is-achieved'fwhen errorsignals frorn'the-brdgelfl rotate'the'motor S4/in 4the'properfdirection to'reduce the value of the inducta-n'ces'20 and 24. lf necessaryto further reduce such inductance, thetvariable inductances 20 'and 4 may-be inserted in the circuit in parallel as shown inFigure 3D. This would occur'i'the inductances 20 and 24 were driven to their minimum value andthe condenser 14 driven through Vits ymaximum value or additionalcircuits actuated asexplained in detail hereinafter. v

Returning to the rstdescribedoperation of the tuning circuits, it will be recalled thatwhen the-inductances Z and 24 are driven to their minimunrvalue, they areY placed in a parallel circuit relation as showninrFigure SB'Whcn the condenser 14 is driven through its maximum value. In certain instances,the motor 54 will continue' to receive error signals romthe magnitudesensitive bridge attempting to furtherrcduce the value of thev inductance'because the value of the inductances 2'0'and` 24 in'parallel will still be too'great at their absolute minimum value to properly tune the antenna to 'the'amplier 1l as"t`ar"a's"themag nitude of impedance is'c'oncerned `ifif:cordingly, provisionhas been made to render the antenna idsomewhat capacitive at this pointin ordervtorequire a greater value of inductance between the antenna 10 and ground to properly match the antenna ltto the arrrplier l1.

It will be remembered that lwhen the armature 62 engaged the contact 64 and the 'armature 89 engaged the contact 91, ajgrounding pulse was furnished through the 'conductor 94 to the vsequence circuit 95 causing the `paralleling 'of thevariable'inductauces '20"and "24. `However, if the 'mot0r54 'permits "the variable inductances 2d aud`24 to remain'attheir minimum' value or if'it returns them to ltheir Vminimum value, and 'the motor f`42 again v--drives'-thefco'ndenser -14 'throughitsmaxm-um value, a further grounding pulse will be 'furnished' to the sequence 'circuit'95 through the conductor 94'forthe same-reason 't wasf'prev'iously furnished. However, at this vtime the relay `'l0l`will "be -energized r by a conductor L110 and the 'armature'29'will-be'disengaged from its-front contact to pla'cethe condenser "36 in'series-withftheantenna 10. At 'the-same time asfthis occurs,"the conductor 108 will'be `removedfrom-groundto deene'rgizethe relay 102 if it -had ypreviouslyibeengrounded. In addition, `theconductor 97 will be'de/energizedresulting'in the'reconnection of the nductances 2'0 and'24 in'series. Thus, the tuning Vele- `ments WiIVbeIretUrned'tO/the circuit arrangement shown :in Figure 3A'With the switch`29 open.

With the last-mentioned *'circuit, 'the variable inductances Z0 `and 24 4may be driven 'to 'their "minimum 'value and thereby switched to .the parallel relation illustrated in 4Figure `3`Bor maybedriven'to their maximum value and `switched tolthe'series relation illustrated in Figure 3C, the condenser 36 at alltimes remaining in series with the 'antenna i10`since thefswitch '29fis open. In this manner, lithas beenifound that aV transmitter power amplifier may be'matched to antennas having Widely differing characteristics,

In the operation `of"th'e"tuning circuits shown in Figure l, a'grounding pulse is furnished to the'sequence circuit 95'throu'gh the conductor 94 when the series connected armatures 62 .and 89 engage their respective contacts '64 and '91. "However, there may be instances'when the induc'tances 20 and 2'4'will be driven to their minimum value to' cause the armatureGZ to engage the'contact 64 but the condenser 114 will`be adjusted 'to provide a resonant condition. Accordiugly,the armature 89 will not engage the Contact l91.

It will be obvious that under such circumstances, although thep'xhase'angle will be zerotoprovide a resonant condition, the impedance magnitude will not be properly matched and ineiiicient operation will result. Accordingly, further circuitry is provided to preclude such a condition, such circuitry including the slow release relay 484 operating in response to the relays 76 and 79 across the motors 54 and 42, respectively. Thus, since the variable inductances will be at their minimum value, the armature 62 will engage the contact 64 to energize the relay 59 and actuate the armature 60 to insert the rectiiier 70 in series with the motor toprevent further actuation of the variable 'inductanccs 20 and '24 in the same physical direction. This action willlprec'lude.anyisigniiicant voltage acrossthe motor 54so that the relay 76 will be deenergized and the armature 77 will drop out. Of course, the armature 80 is already resting onltheback Contact of the relay 79 since the condenser '14 is tuned to resonance resulting in the deenergization of the motor 42. After ashort time .interval, the slow release relay 84 will open .to vplace the armature 85 in Contact with theconductor 96 which effectively places this'switch .in series with the contact 64 and armature 62 toprovide'a .groundingpulse to.the conductor 94 leading to the ,sequence circuit 9'5. Accordingly, the sequence circuit 95-willperform inthe same manner as when the armature 89 engages the contact 91. Further, this same modeof operation may occur when itis neces- ,sary for the condenser'36to beplaced in yseries with the Vantenna I0 due to the variable inductances 20 and 24 lbeing driven to their minimum value in parallel relation. It shouldbe understood `that the capacity range through which the condenserd may be Vvaried is great enough to tune Vanyan'tennas that will normally he encountered to resonance, assuming `'that the impedance ,magnitude between'the antennaandRt-F. source ,aresuitably matched.

In order to'better understan'dthe operationof thetuning circuits described above, rit might beljhelpfultodescrihe a typical 'circuit that may' ber employed vin theaselquenceci1fcuit 95. Therefore, reference ,is made '.to` Figure -2 wherein circuitry is shown which may-'be ,usedinthefsegueuce circuit4 95. Before proceeding with-'a description of these circuits, it should be pointed out that a relay 111, provided with an armature 112 and having its back contact joined by. a conductor 113 to the sequence circuit 95, isenergized by being joined to the terminal X. The armature 112 is also joined to a source of D.C. potential 114. Thus, when the switch 37 is closed, the sequence circuit 95 is cleared by the deenergization of the conductor 113.

Proceeding with the description of Figure 2, the sequence circuit 95 is indicated in broken outline and is shown in its initial cleared condition, i. e., the condition nrwhich it is found immediately after the switch 37 has recycled and the tuning circuits are prepared to match the antenna to the amplifier 11. t

- A grounding pulse on the conductor 94 will complete a circuit from the D.C. source 114 through the armature `11,2, -the conductor 113, a conductor 115, a relay 116 actuating armatures 117 and 118, a conductor 119, an armature 121 of a relay 120a actuatingarmatures 120 to 124, inclusive, and the conductor 94 thereby energizing the relay 116. The armature 117 in swinging to its front contact furnishes a holding circuit for the relay 116 while theconductor 94 is grounded. The grounded armature 118 in engaging its front contact energizes the relay 120a through a conductor 125, the other terminal of the relay v120a being connected by a conductor 126 to the conductor 115. The relay 120a is locked in through a circuit extending from ground through an armature 127 of a relay 128 provided with further armatures 129 and 130,'conductors 131 and 132, the armature 124 and the conductor 133. Also, the actuation of the armature 123 to its front contact applies the potential of the D.C. source 114 to the conductor 97 through the switch 112, the conductor 113 and the armature 123.

i When the conductor 94 is disconnected from ground, the relay 116 will be deenergized. When the next groundingpulse is applied to the conductor 94, a further Yenergizing circuit will be completed through a conductor 135, the armature 117, a conductor 136, the armature 120, a conductor 137, a relay 134, the conductor 115, the conductor 113, the armature 112 to the source 114. Grounded armatures 138 and 139 of the relay 134 will be actuated to lengage their front contacts, and this will remove a ground from the conductor 108 which had previously held the relay 102 energized. When the relay 134 is energized, the relay 12S will also be excited through a circuit including the source 114, the armature 112, the conductor 113, a conductor 140, a conductor 141, the relay 128, a conductor 142, a conductor 143 and the armature 139 to ground. It should also be noted that when the armature l138y engages the front contact of 120a is grounded through the conductor 133, the armature 124, the conductor 132, the conductor 144 and the armature 138.

The energized relay 128 is locked in by virtue of the grounded armature 130 engaging the front contact joined to the conductor 142. Furthermore, the armature 129 engages a front contact to supply the positive potential of the D.C. source 114 to the conductor 110 through the armature 112, the conductors 113 and 140, and the armature 129. It will be evident that when the switch 112 is opened, the sequence circuit 95 will return to its initial condition so that the tuning elements will be connected as shown in Figure 3A. Thus, closing the switch 37 not only causes the motors 42 and 54 to drive their associated tuning elements to a predetermined maximum range as described above but also connects the tuning elements in a predetermined arrangement with respect to the 'antenna 10.

' In examining the above-described circuitry, it will be apparent that the transfer from thenseries to the parallel connection of the variable inductances and 24 is irrever'sible in thesense that the grounding pulse on the condoctor ,94 energizes the relay 120a which remains locked infuntil the. sequence circuit 95 is cleared or the condenser 36 is connected in serieswith `theantenne.' 1Q1 the relay 134, the relay ,will rarely occur. However,

ometers, if employed for the variable inductances 20 and 24, beyond their minimum value to preclude operation thereof over more than degrees of rotation. .It has been found unnecessary to provide for such a function at the maximum value of the inductances 20 and 24 since their transfer to the circuit of Figure 3C will cause them to be driven toward their minimum value if their initial maximum value is of sufficient magnitude. However, if desired, similar provisions may be made to prevent the variometers, if employed, from being driven beyond their maximum value in order to permit the insertion of further tuning elements in the circuit.

While the sequence tuning circuit has been described as comprising the four interconnected relays 116, 12041, 128 and 134, it will be understood that it acts as a stepping switch which could be substituted therefor if desired. Further, it may be preferable in certain instances to initially connect the tuning elements in one of the other arrangements illustrated in Figures 3B, 3C or 3D instead of that shown in Figure 3A. In this event, the remainder of the circuits would be modified accordingly.

To aid in appreciating the advantages of the abovedescribed invention, some typical values of capacity and inductance that have been found useful in the tuning elements will be set forth below. It will be understood, of course, that the invention is not limited to these illustrative values.

The variable condenser 14 may be continuously variable over 360 degrees from 16 to 650 micro-microfarads. The variable inductances, preferably variometers, may be variable from l to 20 microhenries, this range including both their series and parallel connections in the circuit. The series of condenser 36 may have a value of 75 micromicrofarads.

It has been found that an antenna tuner utilizing tuning elements with the above values will match a 52 ohm resistive load over the frequency range from 3 to 18.5 megacycles to the grounded type antennas normally employed on aircraft of the following types:

Lockheed Constellation Douglas DC-4 Boeing 377 Douglas DC-6B y To gain an appreciation of the different antenna characteristics which the antenna tuner must accommodate, the impedances of several antennas at 10 megacycles on the aforementioned aircraft will be listed:

Lockheed Constellation 60-j225 Douglas DC-4 15G-i800 Boeing 377 Y 37+jl5 Douglas DC-6B 11+j209 less the antenna tuner automatically corrected for the mismatch.

It will be understood that the above-described embodif ments of the invention are illustrative only and modifica-.- tions thereof will occur to those skilled in the art. For example, .various types otyariable condensrs could vbtt assenza 11 employedinplacel of theA one shown'in" Figure 1 and, for example, Increductors, aform ofsaturablereactor, could be employed forthe Variable inductances.' Inthis latter case, the means for varying the inductancemay comprise vacuum tubes driven directly by the'error 'signals `from the bridge`12. Therefore; the invention is not to be limited to the specific apparatus disclosed herein but is to be delined by the appende'dclaims:

I claim:

l. Apparatus for tuninga second impedance Vto Va iirst impedance comprising st tuning means series connected between said first impedance and said second impedance, means responsive tothe phase angle mismatch lbetween the first impedance and the'second impedance for adjusting said first tuning means in a direction to eliminate the phase angle mismatch, second tuning means coupled to said second impedance, means responsive'to the magnitude of the impedance mismatch between said first impedance .and said second impedance for adjusting said second tuning means in a direction to eliminate the impedance magnitude mismatch, and control means responsive to the adjustment of said first and second tuning means for selectively inserting said secondtuning means between said second impedance and ground or between said rst tuning means and said second impedance.

2. Apparatus for matching a second impedance to a first impedance comprising variable capacity, means series connected between said first impedance and said second impedance, means responsive to the phase angle mismatch between the first impedance and the second impedance for adjusting said capacity means in a direction to eliminate the phase angle mismatch, variable inductance means coupled to said second impedance, means responsive to the magnitude of the impedance mismatch between said first impedance and said second impedance for adjusting said inductance means in a direction to eliminate the impedance magnitude mismatch, and control means responsive to the adjustment of said capacity means and said inductance means for selectively inserting said inductance between said second impedance and ground or between said capacity means and said second impedance. n

3. Apparatus for matching a second impedance to a first impedance comprising variable capacity means series connected between said first impedance and said second impedance, means responsive to the phase angle mismatch between the first'impedance 'andthe second impedance for adjusting said capacity means'in `a` direction to eliminate the phase angle mismatch, variable inductance means coupled to said second impedance, means responsive to the impedance mismatchl between said firstimpedance and said. second impedance for adjusting said inductance means inadirection to eliminate they impedance magnitude mismatch, a condenser. adapted tol be connected in series with said second impedance, and control means responsive to th'eadju'stment of 'said capacity means and said inductance means forv selectively connecting said inductance means between said second impedance Vand ground or between said capacity means andV said' second impedance and'for selectively connecting said condenser directly to said second impedance in `series with said` capacity means.

i Apparatus for tuning an antenna to a source of radio frequency energy comprising first tuning means series connected 'between said source and said antenna, means responsive tothe phase angle mismatch between the output impedance'of said source and the impedance of said antennafor'adju'sting said Vtirst tuning means in a direction to eliminate'the ph'aseangle mismatch, second tuning means coupled to said antenna, means responsive to the magnitude of the'impedance-mismatchbetween said source andy said antenna foradjusting'said second tuningrneans in'zaf direction to eliminateftheimpedance magnitude 'mismate-li",v -and''control mean's responsive to' the' adjustment ofA 'said 'first and second tuning means .forrsclectively `insertingssaidfsecondt ltuning means` between said :antenna 12 and ground'or between said first tuning means and said antenna.

5. Apparatus fortuning an antenna to a source of radio frequency energy comprising rst tuning means series connected between said source and said antenna, means responsive to the phase angle mismatch between the output impedance of said source and the impedance of said antenna for adjusting said first tuning means in a direction to eliminate the phase angle mismatch, second tuning means coupled to said antenna, means responsive to the magnitude of the impedance mismatch between said source and said antenna for adjusting said second tuning means in a direction to eliminate the impedance magnitude mismatch between said source and said antenna, third tuning means adapted to be connected in series with said antenna, and control means responsive to the adjustment of said first and second tuning means for selectively inserting said second tuning means between said antenna and ground or between said first tuning means and said antenna and for selectively connecting said third tuning means directly to said antenna in series with said first tuning means.

6; Apparatus for tuning an antenna to a source of radio frequency energy comprising variable capacity means series connected between said source and said antenna, means responsive to the phase angle mismatch between the output impedance of said source and the impedance of said antenna for adjusting said capacity means in a direction to eliminate the phase angle mismatch, variable inductance means coupled to said antenna, means responsive to the magnitude of the impedance mismatch between said source and said antenna for adjusting said inductance means in a direction to eliminate the impedance magnitude mismatch, and control means responsive to the adjustment of said capacity means and said inductance means for selectively inserting said inductance means between said antenna and ground or between said capacity means and said antenna.

7. Apparatus for tuning an antenna to a source of radio frequency energy comprising variable capacity means series connected between said source and said antenna, means responsive to the phase angle mismatch between the output impedance of said source and the impedance of said antenna for adjusting said capacity means in a direction to eliminate the phase angle mismatch, variable inductance means coupled to said antenna, means responsive to the magnitude of the impedance mismatch between said source and said antenna for adjusting said variable inductance means in a direction to eliminate the impedance magnitude mismatch, a condenser adapted to be connected in series with said antenna, and control means responsive to the adjustment of said capacity means and said inductance means for selectively inserting said inductance means between, said antenna and ground or between said capacity means and said antenna and for selectively connecting said condenser directly to saidV antenna in series with said capacity means.

8. Apparatus for tuning an antenna to a `source of radio frequency energy comprising Variable capacity means series connected between said source and said antenna, means responsive to :the phase angle mismatch between the output impedance of said source and the impedance of said antenna for adjusting said capacity means in al direction to eliminate the phase angle mismatch, variablel inductance means coupled to said an tenna, means responsive to the magnitudey of the impedance mismatch `between said source and said antenna for adjusting said inductance means in a direction to eliminate the impedance magnitude mismatch, rst control means '.for'initiallyv inserting said inductance means between said antennaand'grou'nd, and second control means responsive to the adjustment of said capacity meansand said inductance' means in a predetermined manner for inserting said` inductance means between said capacity means and saidantenna;

9. Apparatus for tuning an antenna to a source of radio frequency energy comprising variable capacity means series connected between said source and said antenna, means responsive to the phase angle mismatch between the output impedance of said source and the impedance of said antenna for adjusting said capacity means in a direction to eliminate the phase angle mismatch, variable inductance means coupled to said antenna, means responsive to the magnitude of the impedance mismatch between said source and said antenna for adjusting said inductance means in a direction to eliminate the impedance magnitude mismatch, first control means for initially inserting said inductance means between said antenna and ground, and second control means rendered operative upon the adjustment of said inductance means to a predetermined maximum value thereof for inserting said inductance means between said capacity means and said antenna.

10. Apparatus for tuning an antenna to a source of radio frequency energy comprising variable capacity means series connected between said source and said antenna, means responsive to the phase angle mismatch between the output impedance of said source and the impedance of said antenna for adjusting said capacity means in a direction to eliminate the phase angle mismatch, variable inductance means coupled to said antenna, means responsive to the magnitude of the impedance mismatch between said source and said antenna for adjusting said inductance means in a direction to eliminate the impedance magnitude mismatch, a condenser adapted to be connected in series with said antenna, first control means responsive to the adjustment of said capacity means and said inductance means for selectively inserting said inductance means between said antenna and ground or between said capacity means and said antenna, and

second control means responsive to the adjustment of said inductance means to a predetermined minimum value thereof for connecting said condenser directly t said antenna in series with said capacity means.

1l. Apparatus for tuning an antenna to a source of radio frequency energy comprising variable capacity means series connected between said source and said antenna, means responsive to the phase angle mismatch between the output impedance of said source and the impedance of said antenna for adjusting said capacity means in a direction to eliminate the phase angle mismatch, said capacity adjusting means being deactuated upon substantial elimination of the phase angle mismatch, two variable inductances coupled to said antenna, means responsive to the magnitude of the impedance mismatch between said source and said antenna for adjusting said inductances in a direction to eliminate the impedance magnitude mismatch, first control means for initially connecting said inductances in series relation with respect to each other and between said antenna and ground, and second control means responsive to the adjustment of said inductances to a predetermined minimum value thereof for connecting said inductances in parallel relation with respect to each other.

12. Apparatus as defined in claim 11 wherein said second control means includes means operative upon the adjustment of said variable inductances to the predetermined minimum value thereof and the adjustment of said variable capacity means to a predetermined maximum value thereof or upon the deactuation of said capacity adjusting means and the adjustment of said variable inductance means to the prdetermined minimum value for connecting said inductances in parallel relation with respect to each other.

13. Apparatus as defined in claim l2 wherein said inductances comprise variometers.

14. Apparatus for tuning an antenna to a source of radio frequency energy comprising variable capacity means series connected between said source and said antenna, means responsive to the phase angle mismatch between the output impedance of said source and the impedance of said antenna for adjusting said capacity means in a direction to eliminate the phase angle mismatch, said capacity adjusting means being deactuated upon substantial eliminiation of the phase angle mismatch, two variable inductances coupled to said antenna, means responsive to the magnitude of the impedance mismatch between said source and said antenna for adjusting said inductances in a direction to eliminate the impedance magnitude mismatch, first control means for initially connecting said inductances in series relation with respect -to each other and for selectively connecting said inductances between said antenna and ground or between said antenna and said capacity means, a condenser adapted to be connected in series with said antenna, and second control means operative upon the adjustment of said inductances to a rst predetermined minimum value thereof for connecting said inductances in parallel relation with respect to each other, said second control means being operative upon the further adjustment of said inductances in parallel to a second predetermined minimum value thereof for connecting said condenser directly to said antenna in series with said capacity means.

15. Apparatus as defined in claim 14 wherein said second control means includes means operative upon the connection of said condenser to said antenna for connecting said inductances in series relation to each other between said antenna and ground.

16. Apparatus as defined in claim 14 wherein said second control means includes means operative upon the adjustment of said variable inductances to the first or second predetermined minimum value thereof and the adjustment of said variable capacity means to a predetermined maximum value thereof or upon the deactuation of said capacity adjusting means and the adjustment of said variable inductance means to the predetermined minimum value for rendering said second control means operative.

17. Apparatus as defined in claim 16 wherein said inductances comprise variometers.

18. Apparatus as defined in claim 17 wherein means are provided to limit the operation of said variometers to substantially degrees rotation thereof.

19. Apparatus for tuning an antenna to a source of radio frequency energy comprising variable capacity means series connected between said source and said antenna, means responsive to the phase angle mismatch between the output impedance of said source and the impedance of said antenna for adjusting said capacity means in a direction to eliminate the phase angle mismatch, said capacity adjusting means being deactuated upon substantial elimination of the phase angle mismatch, variable inductance means coupled to said antenna, means responsive to the magnitude of the impedance mismatch between said source and said antenna for adjusting said inductance means in a direction to eliminate the impedance magnitude mismatch, first control means for initially inserting said inductance means between said antenna and ground, a condenser adapted to be connected in series with said antenna, and second control means operative upon the adjustment of said inductance means to a predetermined minimum value thereofand the adjustment of said variable capacity means to a predetermined maximum value thereof for connecting said condenser directly to said antenna in series with said capacity means, said second control means being operative upon the adjustment of said inductance means to a predetermined maximum value thereof for inserting said inductance means between said capacity means and said antenna.

20. Apparatus are defined in claim 19 wherein said second control means are also operative upon the adjustment of said inductance means to the predetermined minimum value and the deactuation of said capacity adjusting means for connecting said condenser directly to said antenna in series with said capacity means.

2l. Apparatus as defined in claim 20 wherein said second control means includes means operative upon the Samana connection of said condenser to said antenna for `insert -ing said inductance means between said antenna and ground.

22. Apparatus vfor tuning an antenna to a source of radio frequency energy comprising variable capacity means series connected between said source and said antenna, means responsive to the phase .angle mismatch between the output impedance of said source and the impedance of said antenna for adjusting said capacity means in a direction to eliminate the phase angle mismatch, said capacity adjusting means 'being deactuated upon elimination of the phase angle mismatch, two variable inductances coupled to said antenna, means responsive to the magnitude of the impedance mismatch between said source and said antenna 'for adjusting said inductances in a direetion to eliminate the impedance magnitude mismatch, rst control means for initially connecting said inductances in series relation with respect to each other and between said antenna and ground, acondenser adapted to be connested in series with said antenna, and second control means operative upon the adjustment of said inductances to a iirst predetermined minimum value thereofand the adjustment of said variable capacity means to a predetermined maximum value thereof for connectingsaid inductances in a parallel relation with respect to each other, said second control means operative upon the 'further adjustment of said inductances to a second predetermined minimum value thereof and the adjustment of said variable capacity means to the predetermined maximum value thereof for connecting said condenser directly to -said anrenna in series with said capacity means, said second control 'means being operative upon the adjustment of said inductances to a predetermined maximum value thereof 'for connectingsaid inductances between said capacity means and said antenna.

23. Apparatus as defined in claim 22 wherein said second control means includes means operative upon the connection o f said condenser to said antenna for connects ing said inductances in series relation to eachother between said antenna andground.

24. Apparatus as dened in claim 22 wherein said second control means are also operative upon the adjust- .ment of said inductances to the .first or second predeterthe trst and second impedances, adjusting -the variable inductance means 'to eliminate lthe impedance magnitude mismatch between the iirst and second impedances, and selectively -inserting lthe dvariable inductance -means Vbe- 'tween the -second limpedance -and ground `ortbetween 'the variable capacity means and the second impedance in accordance with the adjustment .of the variable capacity meansand the variable inductance means.

2 8. A' method lfor matching a second impedance to .a 'iirst impedance v4comprising the steps of inserting variable capacity means in .series between said rst and second vimpedances, coupling variable inductance means to said .Second impedance, adjusting the variable capacity means .t0 eliminate the .phase angle mismatch between the rst .and second imp.edances,.adjusting the variable inductance .means toeliminate the impedance magnitude mismatch 'between .the .first ,andsecond impedances, selectively in- .:Serting ,the .variable inductance means between the sec- .Qnd .impedance .and ground or between the variable ca- `pacity ,means and .the second .impedance .in accordance l.with.theadjustment yof the variable capacity means and the variable inductance means, and selectively ,connecting .a condenserdirectly to .the .second impedance .in series with the capacity means in accordance with the adjustment .of .the .variable capacity means andthe variable in- -Aductance means.

29. .A .method for tuning an antenna to a source of radio .frequency `energy comprising the steps of inserting Maria'blecapacity means .inseries between the source and .the zantenna, .coupling .variable inductance means :to the antenna, :adjusting .the -variable capacity means .to elimi- -rnate ,thelphase angle mismatch between .the .output imlpedimos of thefsource and .the impedance of the antenna, adjusting .the wariableinductance means -to eliminate ,the :impedance magnitude mismatch .between the source and zthetantmla, and selectively inserting the variable induct- -.a.nce.;m.eans .between the antenna and .the ground .or .bei-tween the variable capacity @means and the .antenna .in accordance '.withathe adjustment ,of -the .variable .capacity means tand- .the variable .inductance means.

,3.0.. @A method :for-.tuning an ,antenna .to a source :of

. fradiotrequencytenergy .comprising the steps .of inserting variable capacitymeans inseries between'the sourceand the antenna, ,coupling variable inductance means to the antenna, adjusting the variable capacity means to eliminate the .phase .angle mismatch between the source and :the antenna, adjusting fthe'variable inductance meansto eliminate the impedance magnitude mismatch between .the source .and the antenna, selectively inserting the variable inductance 4means between the antenna and the ground or between :the variable -capacity means and the antenna in :accordance with the adjustment of the variable capacity means -and the variable inductance means, and selectively connecting va condenser directly to the antenna in series with the capacity means .in accordance with the adjustment ofthe variable capacity means and the variable in ductance means. 1

References Cited in the file of this patent UNTTED STATES PATENTS .1,758,816 Andrews May 13, 1930 A 1,998,322 Kaar Apr. 16, 1935 2,430,173 vHolmes Nov. 4, A1947 -2,497,202 Beard et al. Feb. 14, 1950 2,505,511 Vogel Apr. 25, 1950 

